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corresponds to approximately 2 mg/dl in a 10-pl sample. Because this sample is diluted to more than 1 ml in the analysis, this detection limit is actually less than 1 ppm of the total analysis volume. The analysis time is generally less than 10 minutes.A unique feature of the method is the pH jump. This technique allows the enzyme to catalyze the reaction of glucose a t a favorable p H for a known length of time. The sudden change of p H to a level favorable to CL emission serves as a timing device for the enzyme reaction. Because of this, the method seems particularly amenable to automation; this aspect is currently under consideration. (Concurrent with this research, Bostick and Hercules (17) have independently developed an automated method for CL glucose analysis employing similar chemical techniques.) In addition, the extension of this technique to other oxidase enzyme systems is anticipated. The method would seem to be applicable to any substrate that yields hydrogen peroxide when it undergoes enzyme catalysis in neutral solution. ACKNOWLEDGMENT The authors thank Vicente Anido who supplied the analyzed human serum samples used in this work. The authors are grateful to D. M. Hercules for supplying a copy of his manuscript prior to publication. The efficiency of electrogenerated chemiluminescence (ECL) (decl) of several systems is reported using both potassium ferrioxalate actinometry and calibrated-photodiode measurements. Experimental methods and necessary corrections in &l-determinations are discussed and ECL in mixed solvent systems ( e.g., acetonitrile (ACN)-benzenetoluene) is described. The following deCl values were found: 9,lO-diphenylanthracene (DPA) (7.8mM), thianthrene (TH) ( 1 l . l m M ) (in mixed solvent): 20% peak efficiency, 5 % for several hours; DPA (7.7mM, in mixed solvent) 4%; DPA (2.20mM, in mixed solvent) 8 % ; rubrene (in benzonitrile) 1.9 YO. Good agreement between pulsed stationary electrode and rotating ring-disk electrode measurements and between actinometric and photodiode determinations was found. Electrogenerated chemiluminescence (ECL) involves the production of excited states, and ultimately light, by the ' Present address, D e p a r t m e n t of Chemistry, L o u s i a n a State '' Present address, Chemical Studies, Air Correction Div., P.O. Li A u t h o r t o w h o m correspondence a n d r e p r i n t requests should University, B a t o n Rouge, L a . 70803. B o x 1107. Darien. Conn. 06820.be sent.

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